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PVA Glue Going Black on Oak

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Togalosh

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Hello Gents,

I understand that tannins in Oak react with iron but can someone enlighten me as to why PVA glue turns black too- but only sometimes ?..I'm pretty sure it doesn't happen all the time.

I know that it should not matter as my joints should be as tight as a gnats chuff so as not to show the glue line ...but there's little chance of that just yet although I am improving very quickly nowadays.

Thanks.
 

James C

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Not sure but for some reason my hands go a purple/black like biro pen is all over them when I handle fresh sawn/planed Oak.

It stains my hands for days sometimes and can transfer back onto the Oak itself. I'm not sure what causes it.
 

stuartpaul

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James C":16qw5kf1 said:
It stains my hands for days sometimes and can transfer back onto the Oak itself. I'm not sure what causes it.
I'm lead to believe that there is a small amount of uric (sp?) acid in our sweat and this reacts with the tanin turning hands black.

When it transfers back onto the oak it's not a problem and easy enough to do that final clean before gule up.

Not sure about the original question though, - I've had PVA squeeze out look black on oak after it's dried. No obvious iron contact - perhaps something in the glue?
 

woodbloke

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phil.p":16uyiqcv said:
I've got some everbuild D4, which is brilliant stuff but smells quite acidic - I'll have find a couple of scraps to try it on.
I use that stuff as well and agree, it's great, but in my experience it doesn't turn black on oak - Rob
 

RogerBoyle

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woodbloke":23k2wjgi said:
phil.p":23k2wjgi said:
I've got some everbuild D4, which is brilliant stuff but smells quite acidic - I'll have find a couple of scraps to try it on.
I use that stuff as well and agree, it's great, but in my experience it doesn't turn black on oak - Rob
I agree
 

MattMoore

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you weren't clamping the boards edge to edge were you? I've had this before where the clamp touches the wood and glue resulting in a small black mark

Sent from my Desire HD using Tapatalk 2
 

Teckel

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MattMoore":yg4mjmyh said:
you weren't clamping the boards edge to edge were you? I've had this before where the clamp touches the wood and glue resulting in a small black mark

Sent from my Desire HD using Tapatalk 2
That happens alright..
 

Togalosh

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:oops: what a plonker I am...I've sussed it out thanks to your help.

..I lost my usual glue bottle nozzle cap & used a steel bolt instead (as a stopper) which has gone rusty.. you get the rest.

It's not funny how a little lack of foresight can cost a lot of grief... & that wisdom is hard won.

Thanks guys.
 

Teckel

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Togalosh":188pejxe said:
:oops: what a plonker I am...I've sussed it out thanks to your help.

..I lost my usual glue bottle nozzle cap & used a steel bolt instead (as a stopper) which has gone rusty.. you get the rest.

It's not funny how a little lack of foresight can cost a lot of grief... & that wisdom is hard won.

Thanks guys.
=D> =D>
 

worsley947

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At least you honest owning up to that :D we all make these simple mistakes :evil:
Dave
 
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